Hall effects on the steady structure of the rotational layer at the dayside magnetopause

Abstract

The influence of the Hall term in the generalized Ohm's law on the large-scale plasma flow during conditions of ongoing magnetic reconnection at the dayside magnetopause ͑MP͒ is investigated. Of special interest is the plasma flow behavior during the transition of the MP transition layer as the Hall effect grows in proportion to the viscous-resistive effects. The governing equations are solved approximately by an ordinary perturbation expansion in orders of large Reynolds and Lundqvist numbers. It is shown that the flow pattern is strongly dependent on the magnitude of the Hall parameter; as it approaches zero, the viscous-resistive solution is obtained, while for an ordering of the same magnitude as the resistivity/viscosity, the Hall effect begins to affect the flow structure severely. For an increasing value on the Hall parameter, oscillations are brought into the system, an effect that is enhanced with the magnitude of the Hall parameter. Furthermore, it is shown that as the Hall effect begins to dominate, the transition layer thickens.

3D MHD reconnection model coupled with Cluster multi‐spacecraft data

“…Having other non‐ideal effects than viscosity and resistivity affecting the dynamical behavior of the plasma together with non‐zero velocity and magnetic field gradients, should reasonably cause a deviation of the plasma flow from the predicted behavior of the analytical model. This has also been indicated from studies of the effects of Hall‐physics on the surrounding plasma flow [ Westerberg and Åkerstedt , 2007c, 2007d].…”

“…For the case of aligned tangential magnetic and velocity fields there is however no controversy, the lowest order tangential magnetic and velocity fields do not depend on the magnetic Reynolds number. The purpose of the present paper is however not to obtain an asymptotic matching of a magnetosheath flow with the intermediate shock layer ‐ which to some extent has been done before numerically by Westerberg et al [2007], but the focus is to see how the solutions of – can be matched with satellite data.…”

“…The HT velocity components are therefore taken as constants equal to their values at the reconnection site such that where superscript ‘0’ represents the value at the reconnection site. See Westerberg and Åkerstedt [2006] and Westerberg et al [2007] for an analysis covering the case of a HT velocity having a gradient in z . In the present work we use data from satellites passing the MP boundary as matching conditions.…”